Number of permutations in S_n avoiding {bar 5}{bar 4}231 (i.e., every occurrence of 231 is contained in an occurrence of a 54231).

A137553

Number of permutations in S_n avoiding {bar 5}{bar 4}231 (i.e., every occurrence of 231 is contained in an occurrence of a 54231).

Terms

    a(0) =1a(1) =2a(2) =5a(3) =14a(4) =43a(5) =146a(6) =561a(7) =2518a(8) =13563a(9) =88354a(10) =686137a(11) =6191526a(12) =63330147a(13) =720314930a(14) =8985750097a(15) =121722964822

External references